Medical ablation device and method of use

ABSTRACT

A tissue resection device includes an elongate shaft having a ceramic working end with a window and a wire-like electrode. A motor oscillates the electrode back and forth in an arc between opposing sides of the window. The working end is engaged against a tissue surface while radiofrequency current is delivered to the wire-like electrode to cut tissue received within the window. A negative pressure source may be connected to the window through an interior passageway in the elongate shaft to extract cut tissue from the working end.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 15/091,402 (Attorney Docket No. 48428-704.30), filed Apr. 5, 2016, now U.S. Pat. No. ______, which is a continuation of International Patent Application No. PCT/US16/25509 (Attorney Docket No. 48428-704.601), filed Apr. 1, 2016, which claims priority from provisional application no. 62/154,595 (Attorney Docket No. 48428-704.101), filed on Apr. 29, 2015, the full disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION 1. Field of the Invention

This invention relates to medical instruments and systems for applying energy to tissue, and more particularly relates to an electrosurgical device adapted for cutting and extracting tissue in an endoscopic procedure.

Various types of medical instruments utilizing radiofrequency (RF) energy, laser energy and the like have been developed for delivering thermal energy to tissue, for example to ablate tissue and to cut tissue. Arthroscopic and other endoscopic electrosurgical tools often comprise treatment electrodes of different configurations where the tools may optionally be combined with irrigation and/or aspiration tools for performing particular minimally invasive procedures. Often the nature of the electrode limits use of a particular tool, and tools must be exchanged during a procedure to perform different tasks.

For these reasons, it would be desirable to provide new and different designs for electrosurgical tools that allow the tools to be re-configured during a procedure to perform different tasks. At least some of these objectives will be met by the inventions described below.

2. Background Art

The disclosure of this application is similar to that of application Ser. No. 13/857,068. Relevant patents and publications include U.S. Pat. No. 5,622,647; 5,672,174; and 7,824,398.

SUMMARY OF THE INVENTION

In a first aspect of the present invention, an electrosurgical device comprises an elongate shaft, typically a tubular shaft, having an axis with an interior channel extending along the axis to an opening in a distal end of the shaft. The channel is configured to be coupled to a negative pressure source, and an electrode with a hook-shaped distal portion is coupled to the shaft and moveable between a first position in which a distal tip of the electrode is disposed at a periphery of the opening and a second position in which the distal tip extends distally beyond the opening. With the distal portion of the electrode in the first position, the tool is particularly useful for surface ablation of tissue such as cartilage. With the distal portion of the electrode in the second position, the tool is particularly useful for cutting tissue structures. In one application, the hook-shaped electrode can be used in a lateral release, which is an arthroscopic procedure for releasing tight capsular structures, e.g., the lateral retinaculum, on the outer or lateral aspect of the kneecap. Such a procedure is performed due to pain related to the kneecap being pulled over to the outer (lateral) side and not being able to move properly in a groove of the femur bone as the knee bends and straightens.

In a second aspect of the present invention, an electrosurgical device comprises an elongate shaft, typically tubular, that extends along an axis with an interior channel extending to an opening with a periphery in a working end. The channel is adapted to be coupled to a negative pressure source. A moveable electrode having a conductive portion with a proximal end and a distal end is coupled to the shaft so that the distal end of the conductive portion is located proximate the periphery of the opening when the electrode is in a proximally retracted position and the distal end of the electrode extends distally beyond the periphery when the electrode is in a distally extended position. With the conductive portion of the electrode in the first position, the tool is particularly useful for surface ablation of tissue and cautery. With the conductive portion of the electrode in the second position, the tool is particularly useful for capturing and cutting tissue structures.

Usually, in both aspects, the electrode of the electrosurgical device is mounted to axially translate between the first and second positions. In another variation, the electrode is mounted to rotate about the axis between the first and second positions. In another variation, the electrode of the electrosurgical device of is mounted to axially translate and/or rotate about the axis between the first and second positions.

In specific embodiments, the electrosurgical device may further comprise a valve in the interior channel for controlling fluid flow therethrough. An exterior of the electrosurgical shaft may comprise a second electrode. The electrosurgical device may further comprise a rotator coupled to the electrode, where the rotator causes the electrode to rotate as it is being axially translated. The opening of the electrosurgical device may define a plane which is angled relative to the axis of the shaft, and the hook-shaped portion of the electrode may be turned so that a back of the hook portion extends outwardly above the plane when the electrode is in the first position. The electrosurgical device may still further comprise a temperature sensor and/or impedance sensing electrodes near a distal end of the shaft. Alternatively, or in addition to the sensors, the electrosurgical device may further comprise a temperature-responsive current limiting element in series with the electrode in order to inhibit or prevent overheating of distention fluid in a treatment site.

In a first specific embodiment, the elongate shaft of the electrosurgical device comprises a ceramic or other tubular body extending along an axis and having a window in a distal portion thereof. The electrode comprises a wire-like electrode configured to rotate in an arc back and forth between opposing sides of the window, i.e. to rotationally oscillate about an axis of the shaft. A motor is operatively connected to the wire-like electrode to rotate or rotationally oscillate the wire-like electrode to cut tissue received in the window. The arc of oscillation will typically be in the range from 10° to 210°, often in the range from 20° to 180°. The oscillation cycle may be in the range from 1 to 100 CPS (Hz), typically being from 5 to 50 CPS. The oscillation rate will typically be adjustable, and the apparatus of the present invention may include a mechanism for effecting such adjustment and/or the motor speed may be controllable. In particular embodiments, the device includes a mechanism that provides a first rate of rotating the electrode in a first rotational direction and a second rate of rotating the electrode in a second opposing rotational direction.

In additional embodiments, the electrosurgical device will be configured to be connected to radiofrequency (RF) source to couple the wire-like electrode to the RF source. Additionally, an interior passageway of the shaft may be connected to communicate with a negative pressure source to help remove excised tissue from the passageway.

In certain embodiments, the wire-electrode of the electrosurgical device may be configured to abut opposing sides of the window at the end of each arc of oscillation. Alternatively, the electrode may be configured to move past the opposing sides of the window in a shearing motion at the end of each cycle of oscillation. The electrosurgical device may further comprise a rotatable drive shaft operatively coupling the wire-like electrode to the motor, said shaft including a shock absorber mechanism to absorb a rotational resistance.

In other specific embodiments, the elongate shaft may comprise an articulating shaft configured to be actuated by a one pull-wire to permit steering of the cutting end during use. Optionally, the wire-electrode may be configured to be moved axially (in addition to the oscillatory motion) relative to the window. Additionally, the wire-like electrode will typically have a hook shape and the elongate shaft will usually have a channel configured to be removably connected to a fluid to deliver a fluid to a distal portion of the shaft.

In a second specific embodiment, the electrosurgical device comprises an elongate shaft with a longitudinal axis end and a distal working end comprising a ceramic body with a window therein. A wire-like electrode is mounted proximate the window and is configured to rotationally oscillate in an arc back and forth between opposing sides of the window to cut tissue received by the window. A motor oscillates the wire-like electrode, and a negative pressure source is coupled to a passageway in the shaft communicating with the window. In particular embodiments, the window will be faced or oriented perpendicularly or at an acute angle (greater than 45°, optionally greater than 60°) relative to the longitudinal axis of the elongate shaft. Optionally, the distal working end of the elongate shaft may be configured to provide an articulating (steerable) working end.

In specific aspects of the second embodiment, the articulating working end of the shaft may comprise a slotted tube actuated by at least one pull-wire. A radiofrequency (RF) current source may be operatively coupled to the electrode, and the elongate shaft will typically have a channel configured to be connected to a fluid source to deliver a fluid through an open port in the working end.

Systems according to the present invention may include a controller adapted to control at least one of the motor operating parameters, the RF source, the negative pressure source, and the fluid source based on a feedback signal. The feedback signal may be provided by the controller in response sensing an operating parameter from at least one of the motor, the RF source, the negative pressure source and the fluid source. In many embodiments, the controller will be configured to adjust at least one of (1) the motor operating parameters in response to feedback signals from at least one of the RF source and the negative pressure source, (2) the RF parameters in response to feedback signals from at least one of the motor operating parameters and the negative pressure source, and (3) the negative pressure parameters in response to feedback signals from at least one of the motor operating parameters and the RF source. The electrode may be configured to axially translate between the first and second positions, and the electrode usually has a hook shape.

In a third specific embodiment, a method for resecting tissue comprises providing an elongate shaft with a working end which typically comprises a tubular or other ceramic body having a window and a motor driven electrode. The electrode is oscillated back and forth in an arc between opposing sides of the window. The working end is engaged against the tissue to cause a volume of tissue to pass through the window, and an RF source delivers RF current to the electrode to cut tissue received through the window. The resected tissue passes into a passageway in the elongate shaft.

In particular aspects of the methods of the present invention, a negative pressure source in communication with the interior passageway in the elongate shaft may be actuated to extract cut tissue from the working end through the interior passageway in the elongate shaft. The tissue may be immersed in a liquid which may optionally be delivered to the tissue from a fluid source to the working end through a flow channel in the elongate shaft. Alternatively, the tissue may be maintained in a gas environment while resecting the tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is side view of an electrosurgical probe corresponding to the invention that includes an elongate shaft extending along an axis to a working end with a re-configurable electrode.

FIGS. 1B and 1C illustrate various embodiments of the re-configurable electrode of FIG. 1.

FIG. 2A is a perspective view of the working end of FIG. 1 with the moveable electrode in a first position.

FIG. 2B is a perspective view of the working end of FIG. 1 with the moveable electrode in a second position.

FIG. 2C is a perspective view of the working end of FIG. 1 with the moveable electrode in a third position.

FIG. 3 is an exploded view of the components of the working end of FIG. 1.

FIG. 4 is a perspective view of a working end of an electrosurgical device similar to that of FIG. 1 with temperature sensor for measuring the temperature of distention fluid in a joint and a controller that can signal an LED to illuminate as a high temperature alert to the physician.

FIG. 5 is a perspective view of the working end of an electrosurgical device similar to that of FIG. 1 with a second electrode arrangement configured to measure impedance in distention fluid in a joint in order to determine the temperature of the fluid.

FIG. 6A is a cut-away perspective view of the working end of an ablation device similar to that of FIG. 1 with a PTCR (positive temperature coefficient of resistance) material in the return electrode assembly which can sense distention fluid temperature to de-activate the electrical path from the return electrode to the RF source.

FIG. 6B is another cut-away view of the working end of FIG. 6A showing an inner sleeve that carries the working end assembly.

FIG. 7 is a perspective view of another variation of an electrosurgical device similar to that of FIG. 1 with a rotatable electrode that is driven by a motor to rotate back and forth in an arc.

FIG. 8 is a cut-away view of the device of FIG. 7 showing a motor and drive mechanism.

FIG. 9 is a perspective view of the working end of the device of FIG. 7.

FIG. 10 is a perspective view of the electrode of the device of FIG. 7 de-mated from the shaft assembly.

FIG. 11 is a perspective view of the electrode and distal ceramic body of the device of FIG. 7.

FIG. 12A is a cross-sectional view of the working end the device of FIG. 9 taken along line 12-12 of FIG. 9, wherein the electrode abuts edges of a ceramic body at the ends of its movement in an arc.

FIG. 12B is a cross-sectional view of a working end similar to that of FIG. 12A wherein the electrode moves past edges of a ceramic body in a shearing motion at the ends of it movement in an arc.

FIG. 13 is a perspective view of a working end of an electrosurgical device similar to that of FIGS. 1 and 7 with an articulating shaft portion.

FIG. 14 is a perspective view of another variation of working end similar to that of FIG. 9 with a fluid source for delivering fluid to the electrode and the working end.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings and the reference numbers marked thereon, FIGS. 1A and 2A-2C illustrate one embodiment of electrosurgical probe 100 that includes a handle portion 104 and an elongate shaft 105 that extends about longitudinal axis 108. FIG. 1 is a schematic view of the probe in which the shaft 105 consists of an assembly further described below having a diameter ranging from about 3.0 mm to 6.0 mm and any suitable length for arthroscopy or another endoscopic procedure. The working end 110 carries an electrode arrangement including a moveable first polarity or active electrode 120 and a second polarity or return electrode 122 operatively coupled to an RF source 125 and controller 130. As can be seen in FIG. 1A, the shaft 105 has a fluid extraction channel 132 in communication with a negative pressure source 135 that can be a wall suction source in an operating room or a pump system in controller 130. In FIG. 2A, it can be seen that fluid channel 132 extends distally to an opening 140 in the working end 110 which is proximate the electrode 120.

In one embodiment in FIGS. 1A and 2A-2C, the first polarity electrode 120 has an elongated medial portion 142 that extends through a passageway 144 (or channel 132) in shaft 105 to an actuator mechanism 146 in the handle 104. The electrode 120 terminates in an electrically conductive portion free from insulation, with the conductive portion typically being hook-shaped as described in more detail below. In FIG. 1A, it can be seen that actuator 146 is adapted to slide from position A to position B to position C to thereby move the electrode 120 from the non-extended position of FIG. 2A to the extended position of FIG. 2B and then to the extended and rotated position of FIG. 2C. Any suitable actuator mechanism known in the art can be used to move the electrode 120 axially and rotationally, and in one variation shown in FIG. 1, a barrel 148 with a spiral groove 152 therein can translate linear motion of the actuator mechanism 146 to rotational motion. In another embodiment, the actuator 146 can be fixed to the proximal end 149 of electrode 120 and adapted to move both axially and rotationally to move the electrode 120 between the various positions shown in FIGS. 2A-2C. The moveable actuator 146 can be configured with detents that engages a portion of handle 104 to releaseably maintain the electrode 120 in one of the selected positions of FIGS. 2A-2C.

Referring again to FIG. 1A, a second actuator 160 in handle 104 is adapted to modulate outflows in fluid extraction channel 132. FIG. 1A shows the extraction channel portion 132′ in handle 104 extends to a quick-connect 162 on handle 104 to which an outflow tubing 164 is coupled that extends to the negative pressure source 135. The actuator 160 can operate any type of suitable valve 165 to control the amount of outflow from a treatment site, such as a knee or shoulder. In such an arthroscopic procedure, the fluid inflows are provided through an independent inflow path which can be through a fluid channel in an endoscope or through another independent cannula accessing the treatment site.

Still referring to FIG. 1A, an electrical cable 166 extends from RF source 125 and controller 130 to the handle 104 with leads in the handle coupled to the first and second electrodes. The system can include a footswitch 168 operatively connected to controller 130 for ON-OFF actuation of RF energy to the electrode arrangement. In another variation, the switch for actuation of RF energy can be positioned in the probe handle 104. The RF source and controller can provide for various power setting as is known in the art, and can use any radiofrequency known in the art for creating a plasma about the electrode 120 for cutting tissue.

Referring to FIGS. 1B and 1C, the active electrode 120 which includes the conductive portion of the electrode extending distally from the medial portion 142 is typically hook-shaped and may have an a square or trapezoidal profile, as shown in FIG. 1B, or may have a curved or arcuate profile, as shown in FIG. 1C. The hook portion will typically have a length L in the range from 3 mm to 10 mm and a depth X in the range from 2 mm to 6 mm. The hook-shaped active electrode will also include a back or a spine region 121 that remains exposed over a plane defined by the opening 140 when the electrode is proximally retracted and a distal tip 190 of the electrode engages or lies proximate to the periphery or perimeter 192 surrounding the opening 140. The distal tip 190 may terminate at, above, or below a centerline 123 of the electrode, as shown in full line and broken lines in FIGS. 1B and 1C.

The exploded view of a portion of the probe of FIG. 3 illustrates the components and assembly of the working end 110. In one variation shown in FIG. 3, the shaft 105 includes an elongate metal sleeve 170 (e.g., stainless steel) that is coupled to handle 104 which provides structural strength to the shaft 105 and further serves an electrical conductor to function as, or connect to, the return electrode 122. The proximal end of sleeve 170 is fixed to handle 104 with an electrical connector (not shown) within the handle coupling the sleeve 170 to cable 166 and a pole of the RF source 125 (see FIG. 1).

In FIG. 3, it can be seen that the distal end 174 of sleeve 170 couples with non-conductive ceramic body 175, which may be formed from a material selected from a group consisting of zirconia, alumina or another similar ceramic, for example being yttria-stabilized zirconia, magnesia-stabilized zirconia, ceria-stabilized zirconia, zirconia toughened alumina, or silicon nitride. In one variation, a reduced diameter proximal end 177 of ceramic body 175 can mate with bore 180 in sleeve 170. FIG. 3 further shows a metal distal body or housing 185 that is configured to slide over ceramic body 175 as a support structure and then is welded to the distal end 174 of sleeve 170 to thus provide the assembled working end of FIG. 2A-2C. The metal distal body or housing 185 then functions as second polarity electrode 122 as can be understood from FIG. 2A-2C. In one variation, a thin-wall dielectric material 186 such a heat shrink material (PFA, FEP or the like) covers the sleeve 170 proximally from the distal metal housing 185 to the handle 104.

In FIG. 3, it can be seen that first polarity electrode 120 and more particularly its medial portion 142 extends through a bore 189 in ceramic body 175. The elongated portion of electrode 120 is covered by a heat-shrink insulator 187 of a material such as FEP or PFA. The distal portion of electrode 120 is configured with bends or curvature to provide a hook-shaped electrode with an outermost electrode surface 188 that is approximately within an envelope defined by the cylindrical periphery of shaft 105 in the position of FIG. 2A. This configuration permits the physician to move or “paint” the outermost surface 188 of electrode 120 across a tissue surface to perform an electrosurgical surface ablation of such tissue. Referring to FIGS. 2A and 3, the distal tip 190 of electrode 120 in the position shown in FIG. 2A is configured to be disposed within or adjacent a periphery or perimeter 192 of opening 140 in the working end. More particularly, distal tip 190 in the position of FIG. 2A is configured to rest in a notch 194 in ceramic body 175. When the distal tip 190 is in the position of FIG. 2A, the tip 190 is distance D of at least 0.010″ (see FIG. 2A) from the closest edge of window 195 of the metal body 185. As can be seen in FIGS. 2A-2C, the window edge 195 of metal body 185 is configured to have notch 200 that is larger than the notch 194 in ceramic body 175 to insure that the first and second electrodes, 120 and 122, are not in close proximity in the electrode position shown in FIG. 2A.

As can be seen in FIGS. 2B and 2C, the hook-shaped distal portion of electrode 120 can be extended axially and optionally rotationally to orient the distal tip 190 and terminal hook portion 196 for electrosurgical cutting of tissue as is known in the art using hook electrode tools. Thus, the electrode 120 is re-configurable to perform electrosurgical surface ablation treatments or electrosurgical cutting treatments. The electrode 120 can be a wire formed of tungsten, stainless steel or any other suitable material having a round, oval or polygonal cross section.

Referring again to FIG. 3, in one variation, it can be seen that the bore 180 in sleeve 170 is lined with a thin-wall dielectric material 198 such as polytetrafluoroethylene (PTFE), Nylon, PFA, FEP, polyethylene or the like which prevents the inner wall of sleeve 170 from functioning as an electrode. In another aspect of the invention, FIG. 4 illustrates a temperature sensing and signaling system that is carried within the working end 220 of a probe similar to that of FIGS. 1-3. Temperature sensing of distention fluid in an arthroscopic procedure is important as the fluid can be heated during any electrosurgical ablation procedure. If the distention fluid is at an elevated temperature for an excessive time period, tissue throughout the joint can be damaged. In FIG. 4, it can be seen a temperature sensor 225 is provided in a surface of the working end which can comprise any form of thermocouple, thermistor or other type of sensor. The sensor 225 is configured to send temperature signals to the controller 130 which can signal the operator of elevated temperature and/or terminate energy delivery from the RF source to the working end 220. In one variation shown in FIG. 4, the controller 130 can signal the physician of a high temperature signal from sensor 225 by illuminating LED lights 240 a and 240 b coupled to electrical source 245 on either side of the working end 220. In such an embodiment, the controller 130 may have algorithms for blinking the LEDs at increasing rates that increase with temperature of the distention fluid. Any combination of visual, aural and tactile signals may be used to alert the physician of elevated temperatures in the distention fluid. In another embodiment (not shown), the temperature sensor 225 can actuate at least one light source in the controller that is coupled to optical fibers to carry light to light emitters in the working end. In another variation, a plurality of different wavelength light sources in the controller can send different wavelengths to the emitter(s) in the working end to indicate different temperatures of the distention fluid.

FIG. 5 illustrates another temperature sensing system that can be carried by the working end 220 as in FIG. 5. In FIG. 5, spaced apart first and second electrodes, 252 a and 252 b are provided in insulated surface 254 of the probe shaft 255. The electrodes 252 a and 252 b are coupled to an electrical source 255 and controller 130 which is configured to measure an electrical parameter of the distention fluid, for example impedance or capacitance of a saline distention fluid. The measured electrical parameter then can be compared to known values of saline at various temperatures in a look-up table to determine fluid temperature. The calculated temperature then can actuate any visual, aural or tactile signal to alert the physician of elevated temperatures in the saline.

FIGS. 6A-6B illustrate another embodiment of the present invention that integrates a temperature sensing mechanism with the return electrode to control energy delivery to tissue. As can be seen in FIG. 6A, the working end 260 of a probe is similar to that of FIGS. 1-3. However, the distal metal housing 265 does not function as a return electrode. The metal housing 265 is not welded to elongate sleeve 270 which is electrically coupled to RF source 125 and controller 130. Rather, an independent return electrode sleeve 275 with a short length is positioned proximally from the distal metal housing 265. In one variation, an insulative ceramic collar 277 separates the distal metal housing 265 from the return electrode sleeve 275. The temperature-sensing component of the working end 260 comprises a polymer PTCR (positive temperature coefficient of resistance) sleeve 280 that forms an intermediate electrical connector between the return electrode sleeve 275 and sleeve 270. The sleeve is electrically coupled to RF source 125 (see FIG. 1). The return electrode sleeve 275, the PTCR sleeve 280 and sleeve 270 can be mounted over insulated support sleeve 285 shown in FIG. 6B. The PTCR material of sleeve 280 allows conduction of RF current therethrough within a selected low temperature range, but can prevent current flow through the sleeve at a selected elevated temperature. As can be seen in FIGS. 6A-6B, the proximal end 282 of the return electrode 275, the PTCR sleeve 280 and the elongate sleeve 270 is covered with a thin-wall insulator 288 to thus prevent conductive saline contact with this portion of the probe. As can be understood in FIGS. 6A-6B, the thin-wall insulator 288 allows heat transfer from the distention fluid through the insulator 288 to the PTCR sleeve 280 which then can cause the PTCR sleeve to become non-conductive to terminate current flow from the return electrode 275 to the RF source 125. By this means, the PTCR mechanism can terminate RF energy delivery in response to elevated temperatures in the distention fluid. The PTCR material can be selected to have a any suitable switching temperature, for example any temperature between about 40° C. and 45° C. Suitable polymer PTCR materials can be fabricated by Bourns, Inc. 3910 Freedom Circle, Ste. 102, Santa Clara, Calif. 95954.

FIGS. 7-9 illustrate another variation of electrosurgical device 400 that has a similar working end 410 with a hook-shaped electrode 415 but this variation includes a motor 420 for driving the electrode rotationally in an arc to cut tissue in the window 422 (FIG. 9) of the working end. In this variation, a handle portion 424 is connected to elongate shaft 425 that extends about longitudinal axis 428. FIGS. 7-9 are schematic views of the device wherein the shaft 425 consists of an assembly which can have a diameter ranging from about 3.0 mm to 6.0 mm for arthroscopic procedures and can range up to 10 mm or 15 mm in diameter for other endoscopic procedure. The working end 410 again has a wire-like electrode 415 that can be extended to axially to use as a hook as described previously. The working end 410 comprises a ceramic body 426 which can be a form of zirconia, alumina or another similar ceramic as described previously. The electrode 415 comprises a first polarity or active electrode and the second polarity or return electrode 440 can be an outer surface of at least a portion shaft 425. The electrode 415 is operatively coupled to an RF source 445 and controller 450. The shaft 425 again has a fluid extraction channel or passageway 452 in communication with a negative pressure source 455 that can be a wall suction source in an operating room or a pump system in controller 450. As can be seen in FIG. 9, the fluid extraction channel 452 extends distally to the window 422 in the working end 410 which is below the electrode 415.

In general, the electrosurgical device corresponding to the invention comprises a proximal handle 424 coupled to an elongate shaft 425 extending along an axis 428 to a window 422 in a distal ceramic body 426 forming a portion of the shaft and a wire-like electrode 415 driven by a motor 420 to rotate in an arc back and forth between opposing sides 460 a and 460 b of window 422 to cut tissue received by the window. The tissue can be suctioned into the window by the negative pressure source 455. FIG. 8 shows a cut-away view of handle 424 with motor 420 therein. The motor is connected to a mechanism 464 that converts the motors rotational motion to a back and forth movement of the electrode the arc shown in FIG. 12. In one variation, the electrode 415 can move in an arc that ranges between 10° and 210° to cooperate with a window 422 that has the corresponding dimensional arc. In another variation, the electrode arc ranges between 20° and 180°.

The motor 420 can be electric and is geared to rotate or rotationally oscillate the electrode 415 in a back and forth cycle at a rate between 1 cycle per second (CPS or Hz) and 100 cycles per second. The system can be actuated by an actuator or trigger 470 in handle 424. In one variation, the actuator can include a variable speed mechanism for adjusting the rate of rotating or oscillating the electrode 415 back and forth. In another variation, the electrosurgical device 400 can include a mechanism for providing a first rate of rotating the electrode in a first rotational direction and a second rate of rotating the electrode in a second opposing rotational direction. During operation, the RF source and electrode can be activated in a first mode or cutting mode as is known in the art.

As can be understood from FIGS. 7-9, the controller 450 is adapted to control the motor, the RF source and the negative pressure source, and in one variation the controller is configured to adjust RF parameters in response to feedback signals from at least one of the motor's operating parameters and the negative pressure source. In another variation, the controller is configured to adjust motor operating parameters in response to feedback signals from at least one of the RF source and the negative pressure source. In another variation, the controller is configured to adjust negative pressure parameters in response to feedback signals from at least one of the motor operating parameters and the RF source.

In another variation, the device 400 and controller upon de-activation of the actuator will stop rotation of the electrode in a selected position relative to the window, for example in the middle of the window as shown in FIG. 9 or at an edge of the window. In either orientation, the electrode can be activated in a second or “coagulation” mode for coagulating tissue as known in the art.

In a further variation as shown in FIG. 12A, the electrode 415 is adapted to rotationally oscillate within the window so that the electrode abuts opposing sides 460 a and 460 b of window 422 at the end of each arc of rotation. In another variation as shown in FIG. 12B, the electrode 415 can be configured to sweep past the opposing sides 460 a and 460 b of window 422 in a shearing motion at the end of each arc of rotation.

FIGS. 8, 10 and 11 schematically show electrode 415 coupled to a rotatable drive shaft 472 that is operatively coupled to motor 420, wherein the shaft 472 includes a shock absorber mechanism 474 to absorb a rotational resistance such as when the electrode is rotated to abut a side of the window. The shock absorber mechanism 474 can be a spring or resilient drive shaft as is known in the art.

In general, a method of the present invention for resecting tissue comprises providing an elongate member or shaft having a ceramic working end with a laterally disposed window, e.g. an opening or cut-out in a wall of the working end of the elongate member or an opening in a distal ceramic body which faces perpendicularly or at an acute angle relative to a longitudinal axis of the working end, and a motor driven electrode adapted to rotate back and forth in an arc between opposing sides of the window, positioning the working end in an interface with tissue, and actuating the motor and an RF source to thereby cut tissue received by the window with the moving electrode, resulting in pieces or “chips” of cut tissue in an interior of the working end. The method may further comprise actuating a negative pressure source to extract the pieces or “chips” of tissue from the working end through the interior passageway in the elongate shaft. In some embodiments, the method can be performed with tissue interface submerged in saline or other electrically conductive liquid. In other embodiments, the method can be performed in a gas environment, typically with saline or other electrically conductive liquid being delivered from an external source to the working end through a flow channel in the elongate shaft.

FIG. 13 shows another variation of the electrosurgical device with an articulating shaft portion 478 proximate to the working end 410. The articulating shaft can be actuated by a pull-wire 479 in a slotted tube as is known in the art.

FIG. 14 shows another variation of the electrosurgical device wherein a fluid source 480, such as saline, is provided in fluid communication with a flow channel 482 in the shaft 425 to deliver fluid to the working end and electrode 415. The inflow of fluid can provide fluid to flow through the device to assist in extracting cut tissue, or can be use to flood the electrode if operating in a gas environment. In another variation, the electrode (not shown) can be a hollow tube coupled to the fluid source 480 with the electrode 415 having one or more ports for fluid flow therethrough in the exposed electrode portion that cuts tissue in the window.

Although particular embodiments of the present invention have been described above in detail, it will be understood that this description is merely for purposes of illustration and the above description of the invention is not exhaustive. Specific features of the invention are shown in some drawings and not in others, and this is for convenience only and any feature may be combined with another in accordance with the invention. A number of variations and alternatives will be apparent to one having ordinary skills in the art. Such alternatives and variations are intended to be included within the scope of the claims. Particular features that are presented in dependent claims can be combined and fall within the scope of the invention. The invention also encompasses embodiments as if dependent claims were alternatively written in a multiple dependent claim format with reference to other independent claims. 

1. (canceled)
 2. A method of resecting tissue, comprising: providing an elongate shaft with a working end having a window and a motor driven electrode adapted to move back and forth in an arc between opposing sides of the window; positioning the working end against the tissue to cause tissue to interface with the window; and actuating the motor and an RF source to cut tissue interfacing with the window with the moving electrode, wherein the cut tissue enters an interior in the elongate shaft.
 3. The method of claim 2 further comprising actuating a negative pressure source in communication with the interior passageway in the elongate shaft to extract cut tissue from the working end through the interior passageway in the elongate shaft.
 4. The method of claim 2 wherein the motor driven electrode comprises a wire-like electrode, wherein actuating the motor causes the wire-like electrode to rotationally oscillate in an arc back and forth between opposing sides of the window.
 5. The method of claim 4 wherein the arc ranges between 60° and 210°.
 6. The method of claim 4 wherein the arc ranges between 90° and 180°.
 7. The method of claim 4 wherein the electrode is rotationally oscillated in a back and forth cycle at a rate between 1 cycle per second and 50 cycles per second.
 8. The method of claim 7 further comprising adjusting an oscillation rate of the electrode.
 9. The method of claim 4 wherein the device the motor is operated to rotationally oscillate the wire-like blade at a first rate in one direction and at a second rate in another direction.
 10. The method of claim 2 further comprising delivering RF energy to the electrode.
 11. The method of claim 2 further comprising drawing a negative pressure source in an interior passageway in the elongate shaft.
 12. The method of claim 11 further comprising controlling the motor operating parameters, the RF source, and the negative pressure source with a controller.
 13. The method of claim 12 wherein the controller adjusts at least one of (1) the motor operating parameters in response to feedback signals from at least one of the RF source and the negative pressure source, (2) the RF parameters in response to feedback signals from at least one of the motor operating parameters and the negative pressure source, and (3) the negative pressure parameters in response to feedback signals from at least one of the motor operating parameters and the RF source.
 14. The method of claim 12 further comprising stopping oscillation of the wire-like electrode in a selected position relative to the window with the controller.
 15. The method of claim 14 further comprising delivering coagulation RF energy to tissue when the electrode is in the stopped position by the controller.
 16. The method of claim 2 further comprising articulating a distal end of the elongate shaft using a pull-wire.
 17. The method of claim 2 further comprising moving the motor driven electrode axially relative to the window.
 18. The method of claim 2 wherein the wire-like electrode has a hook shape.
 19. The method of claim 2 wherein the elongate shaft has a channel configured to be removably connected to a fluid to deliver a fluid to a distal portion of the shaft. 